This invention relates to a distributor for an electric spark ignitor in an internal combustion engine. More particularly, it relates to an improved rotating electrode of the distributor, by which the field intensity of noise to be radiated at a discharge is reduced.
Noise electric waves which are generated by discharges in the ignition device of an internal combustion engine such as automobile engine, especially in a distributor, have frequency components over a wide range likewise to noise electric waves which are generated by the discharge of an ignition plug. They also extend over a wide range spatially, and exert evil effects on television and radio sets in the surroundings besides electronic circuits within an automobile.
In order to reduce such noise electric waves, various systems and methods have heretofore been devised and put into practical use. It has been known that the use of an ignition plug with a resistor or a high tension cable made up of a high resistance wire of carbon is very effective for reducing the generation of the noise electric waves in the ignition plug. On the other hand, as regards the noise electric waves which are generated from the distributor, various devices and systems have been proposed, but any means exhibiting a satisfactory effect has not been obtained yet.
For example, Japanese Pat. Publication No. 51-38852 discloses a distributor having a rotating electrode whose discharge electrode portion is coated with a high resistance substance layer made of copper oxide, aluminum oxide, silicon oxide, nickel oxide, an oxide of a nickel-aluminum alloy, or the like.
Japanese Pat. Publication No. 51-38853 discloses a distributor having a rotating electrode whose discharge electrode portion is coated with a high resistance substance layer made of silicon oxide, aluminum oxide, an oxide of an iron-nickel alloy, or the like.
Even the distributors of such constructions, however, have low suppressive effects for noise electric wave components of and above 300 MHz.